Track assembly for an all-terrain vehicle

ABSTRACT

The present invention provides track assemblies and a method that allow bringing the contact patch towards the inside (the outside) of the suspension arm, by providing a asymmetric track assembly, either by lowering at least one inside (outside) support wheel relative to the remaining support wheels, or by using a belt that comprises, transversally, at least one first profile on the outer (inner) side thereof lower than a second profile on an inner side thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority on Canadian application no. 2,606,039,filed on Oct. 3, 2007. All documents above are herein incorporated byreference with a track assembly for an all-terrain vehicle.

FIELD OF THE INVENTION

The present invention relates to ATV. More specifically, the presentinvention is concerned with a track assembly for an all-terrain vehicle.

BACKGROUND OF THE INVENTION

As well known in the art, a track system may be installed on a wheeledATV (or other wheeled recreational, industrial or agriculturalvehicles), to provide an—at least partly—, temporarily, tracked ATV.

The resulting contact area between an endless belt of the trackedvehicle and the underlying ground surface, referred to as patch, islarger than the contact area, or patch, of a corresponding wheel of thevehicle when wheeled on the underlying ground surface, therebyincreasing flotation of the vehicle, over smooth terrains such as snowfor example.

A drawback is that, generally, this increased contact patch involves anincreased area of friction, which needs to be opposed for steering. As aresult, it is increasingly harder to rotate the patch around a pivotsteering point and steering effort submitted to such a tracked vehicleis higher than to a corresponding wheeled vehicle, i.e. the ATV on itswheels for example.

Using endless belts having a curved transverse geometry allows reducingthis problem by allowing an increased contact surface when needed, whilemaintaining a reduced contact surface on hard surfaces for example.

However, there is still a need in the art for a track assembly for anall-terrain vehicle.

SUMMARY OF THE INVENTION

More specifically, there is provided a vehicle having a main frame andsupported on the ground by at least two track assemblies, each trackassembly comprising a longitudinal endless belt tensioned around cornerwheels and a sprocket wheel, and support wheels provided on a lower runof the longitudinal endless belt, on each side of a suspension arm ofthe main frame, wherein each track assembly comprises a laterallyasymmetric structure comprising at least one of: i) at least one of thesupport wheels, on one of: i) an inward side and ii) an outward side ofthe suspension arm, located at a lower position in relation to remainingsupport wheels; and ii) the belt laterally comprising regions ofdifferent profiles.

There is provided a drive system for a vehicle having a main framesupporting an engine and a body of the vehicle and steering deviceconnected to the main frame, a longitudinal endless belt, disposed onthe frame of the drive system and connected to the engine to propel thevehicle, being tensioned around corner wheels and a sprocket wheel,support wheels being provided on a lower run of the longitudinal endlessbelt, on each side of a suspension arm of the main frame, the drivesystem comprising a first lateral region and a second lateral region,the lateral regions being defined by at least one of: i) the endlessbelt laterally comprising regions of different profiles; and ii) atleast one of the support wheels, on one of: i) an inward side and ii) anoutward side of the suspension arm, being located at a lower position inrelation to remaining support wheels.

There is further provided a track assembly for a wheeled vehicle,comprising a longitudinal endless belt tensioned around corner wheelsand a sprocket wheel, and support wheels provided on a lower run of thelongitudinal endless belt, on each side of a suspension arm of the mainframe, wherein each track assembly comprises a laterally asymmetricstructure comprising at least one of: i) at least one of the supportwheels, on one of: i) an inward side and ii) an outward side of thesuspension arm, located at a lower position in relation to remainingsupport wheels; and ii) the belt laterally comprising regions ofdifferent profiles.

Other objects, advantages and features of the present invention willbecome more apparent upon reading of the following non-restrictivedescription of embodiments thereof, given by way of example only withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings:

FIG. 1 is a front left-elevation view a vehicle according to anembodiment of an aspect of the present invention.

FIG. 2 is a partial top view of a track assembly according to anembodiment of an aspect of the present invention;

FIG. 3 is a side view of a track assembly according to an embodiment ofan aspect of the present invention;

FIG. 4 is a cross section of the track assembly of FIG. 2;

FIG. 5 illustrates a belt of a track assembly according to a furtherembodiment of the present invention;

FIG. 6 are upper partial perspective views of: a) an asymmetric belt andb) an asymmetric belt having a generally convex transverse profile, fora track assembly according to a further embodiment of the presentinvention;

FIG. 7 is a cross section of a belt having a generally convex transverseprofile.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As illustrated in FIG. 1, a vehicle 10 according to an embodiment of anaspect of the present invention generally comprises a body 12 with aseat 13 for accommodating a rider (nor shown) who uses handlebars 14,for example, to steer the vehicle. The body 12 is supported by trackassemblies 16 in the front and track assemblies 18 in the back, in placeof front and rear wheels respectively in the case of a wheeled vehicle,symmetrically about a vertical axis 20.

The track assemblies may be operatively connected to the engine (notshown) to propel the vehicle 10.

As best seen in FIG. 1, a track assembly typically comprises alongitudinal endless belt 22 tensioned around corner wheels 24, 26 and asprocket wheel 28. The track assembly is removably connected to a hub 30by a frame 32; the hub 30 corresponding to the one previously connectinga wheel of the wheeled vehicle and providing rotational motion to thatwheel for example.

In FIG. 3, the hub 30 transfers its rotational motion to the sprocketwheel 28 that turns the track assembly around the same hub axis 30 andsprocket axis 35 by contact with the endless belt 22. The sprocket 28and frame 32 are independently rotatable about hub 30.

Support wheels 34 are provided, on a lower run of the endless belt 22,on each side of a suspension arm 36 of the main frame 32 best seen inFIGS. 2 and 4 for example.

The endless belt 22 of each track assembly is typically an endlessreinforced rubber belt, having a ground engaging surface and an innersurface. The ground-engaging surface may be provided with traction lugsthat engage the underlying ground surface, whereas the inner surface isprovided with driving lugs that engage the wheels.

The endless belt 22 may have a generally convex transverse profile, fromthe outward peripheral edge to the inner peripheral edge thereof, toprovide a limited contact surface with the underground when theunderground is hard, as known in the art (see FIG. 7).

When replacing a tire of a vehicle by a track assembly withoutmodification of the geometry of the vehicle, the contact area, nowbetween the endless belt and the underground surface, is generallyshifted outward relative to the contact patch previously between thetire and the underground surface. It is found that by lowering an innersupport wheel, the contact patch may be repositioned.

In a first embodiment of the present invention, as illustrated in FIGS.2 to 4, the contact patch of the track system is shifted laterally inrelation to the suspension arm 36, either inwards or outwards, byproviding that at least one support wheel 34 be lower that the remainingones, on the inward side or the outward side of the suspension arm 36respectively.

Thus, as illustrated in FIG. 3, inside support wheels 34 i may belowered slightly relative to outside support wheels 34 o, so as to shiftthe contact patch laterally inwards, i.e. away from the outwardperipheral edge 50 of the width of the belt 22 (see FIG. 1).

Providing at least one support wheel lower that the remaining supportwheels, on the inside of the main suspension arm, thus allows that thecontact patch, provided by this at least one lower support wheel, ispositioned at the location it used to be when the vehicle, conceived fortires, was on tires.

As known in the art, support wheels 34 may further be arranged in tandemin order to alleviate the load on the contacts points created, as tandem38 shown in FIG. 2, which frame 44 is mounted by pivot 42 to thesuspension arm 36 of the main frame 32.

The frame 44 of the tandem 38 of these inside support wheels 34 i, whichare thus in the contact patch, being mounted on the pivot 42 (FIG. 2),is able to adapt and conform to the underground terrain.

In such an arrangement, by providing that at least one lower supportwheel is mounted on a secondary frame 44 pivotally connected to the mainsuspension arm so that the motion of the secondary frame is relativelyindependent from the rest of the track assembly, the generated contactpatch moves as requested by the movement of the vehicle, for instancewhen the track pivots around a vertical axis for the vehicle being ableto turn.

As shown in FIG. 4, the axle 45 of the tandem 38 with lowered supportwheels may be provided with rubber bushings 46, for a soft suspension 44independent from the main suspension 32, by providing a furthercushioning versus shocks, and further improved adaptation to theunderground terrain.

In a second embodiment illustrated for example in FIGS. 5 and 6, thecontact patch of the track system is shifted laterally in relation tothe suspension arm 36 by providing that the belt 22′ comprises,transversally, at least one first profile 22′a on the outer sidethereof, and a second profile 22′b on an inner side thereof. Byproviding that the second profile 22′b on an inner side is higher thatthe first profile 22′a, the contact patch is thus brought towards theinside of the suspension arm 36.

Therefore, the contact patch of a track system may be shifted laterallyin relation to the suspension arm 36, inwards (or outwards), byproviding a asymmetric track assembly, either by lowering at least oneinside (outside) support wheel relative to the remaining support wheels,or by using a belt that comprises, transversally, at least one firstprofile on the outer side thereof lower (higher) than a second profileon an inner side thereof.

As people in the art will appreciate, an asymmetric track according tothe present invention may combine at least one inside support wheellowered relative to the remaining support wheels and a varying-profilebelt, as described hereinabove.

Therefore, the present invention provides track assemblies and a methodthat allow bringing the contact patch towards the inside of thesuspension arm 36, thereby repositioning the normal tire contact patch,i.e. the contact patch of the vehicle when on wheels. As a result, thesteering effort of the track system is reduced to a minimum in a rangeof conditions, including snow, dirt, asphalt, rocks, etc, for example.

Therefore, according to an aspect of the present invention, there isprovided a vehicle comprising at least two asymmetric track assembliesreplacing wheels of a wheeled vehicle.

A suspension as described herein may be applied to a range of wheeledvehicles, such as for example recreational vehicles, ATV, lightindustrial vehicles, industrial vehicles, agricultural vehicles andmilitary vehicles.

The present invention allows reducing the steering effort in suchvehicles, which geometry of the suspension is specifically designed forwheels, to a minimum in all conditions, snow, dirt, asphalt, rocks, etc.

Although the present invention has been described hereinabove by way ofembodiments thereof, it may be modified, without departing from thenature and teachings of the subject invention as defined in the appendedclaims.

1. A vehicle having a main frame and supported on the ground by at leasttwo track assemblies, each track assembly comprising: a longitudinalendless belt tensioned around corner wheels and a sprocket wheel; andsupport wheels provided on a lower run of the longitudinal endless belt,on each side of a suspension arm of the main frame; wherein each trackassembly comprises a laterally asymmetric structure, said laterallyasymmetric structure comprising at least one of: i) at least one of saidsupport wheels, on one of: i) an inward side and ii) an outward side ofthe suspension arm, located at a lower position in relation to remainingsupport wheels; and ii) said belt laterally comprising regions ofdifferent profiles.
 2. The vehicle of claim 1, said laterally asymmetricstructure comprising at least one of: i) at least one support wheellocated on an inward side of the suspension arm; and ii) a first profilein an inner lateral region of said belt higher than a second profile ofan outer lateral region of said belt.
 3. The vehicle of claim 1, whereineach track assembly is removably connected to a hub by the main frame,said hub transferring its rotational motion to the sprocket wheel thatturns the track assembly around an axis of said hub and a sprocket axisby contact with the endless belt.
 4. The vehicle of claim 17 wherein atleast two support wheels are arranged in tandem on at least one side ofthe suspension arm of the main frame.
 5. The vehicle of claim 4, whereinsaid tandem is located at a lower position in relation to the remainingsupport wheels.
 6. The vehicle of claim 5, wherein said tandem is atandem of inner support wheels.
 7. The vehicle of claim 6, wherein aframe of said tandem of inner support wheels is mounted to said mainframe by a pivot.
 8. The vehicle of claim 7, wherein said tandem ofinner support wheels is mounted about said pivot with rubber bushings.9. The vehicle of claim 1, wherein said endless belt has a generallyconvex transverse profile, from an outward peripheral edge thereof to aninner peripheral edge thereof.
 10. The vehicle of claim 1, selected fromthe group comprising recreational vehicles, ATV, light industrialvehicles, industrial vehicles, agricultural vehicles and militaryvehicles.
 11. A drive system for a vehicle having a main framesupporting an engine and a body of the vehicle and steering deviceconnected to said main frame, a longitudinal endless belt, disposed onsaid frame of said drive system and connected to the engine to propelthe vehicle, being tensioned around corner wheels and a sprocket wheel,support wheels being provided on a lower run of said longitudinalendless belt, on each side of a suspension arm of the main frame, saiddrive system comprising a first lateral region and a second lateralregion, said lateral regions being defined by at least one of: i) saidendless belt laterally comprising regions of different profiles; and ii)at least one of said support wheels, on one of: i) an inward side andii) an outward side of the suspension arm, being located at a lowerposition in relation to remaining support wheels.
 12. The drive systemof claim 11, wherein said lateral regions are defined by at least oneof: i) said endless belt laterally comprising regions of differentprofiles; and ii) at least two of the support wheels being located at alower position in relation to remaining support wheels, said at leasttwo support wheels being mounted in a tandem.
 13. The drive system ofclaim 12, wherein said lateral regions are defined by at least one of:i) said endless belt laterally comprising regions of different profiles;and ii) at least two of the support wheels being located at a lowerposition in relation to remaining support wheels, said at least twosupport wheels being mounted in a tandem having a frame pivotallyconnected to said main frame.
 14. A track assembly for a wheeledvehicle, comprising: a longitudinal endless belt tensioned around cornerwheels and a sprocket wheel; and support wheels provided on a lower runof the longitudinal endless belt, on each side of a suspension arm ofthe main frame; wherein each track assembly comprises a laterallyasymmetric structure, said laterally asymmetric structure comprising atleast one of: iii) at least one of said support wheels, on one of: i) aninward side and ii) an outward side of the suspension arm, located at alower position in relation to remaining support wheels; and iv) saidbelt laterally comprising regions of different profiles.